1 files changed, 506 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/audio/Sonic.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/audio/Sonic.java
new file mode 100644
index 0000000000..1a0dad4b45
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/audio/Sonic.java
@@ -0,0 +1,506 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ * Copyright (C) 2010 Bill Cox, Sonic Library
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.mozilla.thirdparty.com.google.android.exoplayer2.audio;
+
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions;
+import java.nio.ShortBuffer;
+import java.util.Arrays;
+
+/**
+ * Sonic audio stream processor for time/pitch stretching.
+ * <p>
+ * Based on https://github.com/waywardgeek/sonic.
+ */
+/* package */ final class Sonic {
+
+  private static final int MINIMUM_PITCH = 65;
+  private static final int MAXIMUM_PITCH = 400;
+  private static final int AMDF_FREQUENCY = 4000;
+  private static final int BYTES_PER_SAMPLE = 2;
+
+  private final int inputSampleRateHz;
+  private final int channelCount;
+  private final float speed;
+  private final float pitch;
+  private final float rate;
+  private final int minPeriod;
+  private final int maxPeriod;
+  private final int maxRequiredFrameCount;
+  private final short[] downSampleBuffer;
+
+  private short[] inputBuffer;
+  private int inputFrameCount;
+  private short[] outputBuffer;
+  private int outputFrameCount;
+  private short[] pitchBuffer;
+  private int pitchFrameCount;
+  private int oldRatePosition;
+  private int newRatePosition;
+  private int remainingInputToCopyFrameCount;
+  private int prevPeriod;
+  private int prevMinDiff;
+  private int minDiff;
+  private int maxDiff;
+
+  /**
+   * Creates a new Sonic audio stream processor.
+   *
+   * @param inputSampleRateHz The sample rate of input audio, in hertz.
+   * @param channelCount The number of channels in the input audio.
+   * @param speed The speedup factor for output audio.
+   * @param pitch The pitch factor for output audio.
+   * @param outputSampleRateHz The sample rate for output audio, in hertz.
+   */
+  public Sonic(
+      int inputSampleRateHz, int channelCount, float speed, float pitch, int outputSampleRateHz) {
+    this.inputSampleRateHz = inputSampleRateHz;
+    this.channelCount = channelCount;
+    this.speed = speed;
+    this.pitch = pitch;
+    rate = (float) inputSampleRateHz / outputSampleRateHz;
+    minPeriod = inputSampleRateHz / MAXIMUM_PITCH;
+    maxPeriod = inputSampleRateHz / MINIMUM_PITCH;
+    maxRequiredFrameCount = 2 * maxPeriod;
+    downSampleBuffer = new short[maxRequiredFrameCount];
+    inputBuffer = new short[maxRequiredFrameCount * channelCount];
+    outputBuffer = new short[maxRequiredFrameCount * channelCount];
+    pitchBuffer = new short[maxRequiredFrameCount * channelCount];
+  }
+
+  /**
+   * Queues remaining data from {@code buffer}, and advances its position by the number of bytes
+   * consumed.
+   *
+   * @param buffer A {@link ShortBuffer} containing input data between its position and limit.
+   */
+  public void queueInput(ShortBuffer buffer) {
+    int framesToWrite = buffer.remaining() / channelCount;
+    int bytesToWrite = framesToWrite * channelCount * 2;
+    inputBuffer = ensureSpaceForAdditionalFrames(inputBuffer, inputFrameCount, framesToWrite);
+    buffer.get(inputBuffer, inputFrameCount * channelCount, bytesToWrite / 2);
+    inputFrameCount += framesToWrite;
+    processStreamInput();
+  }
+
+  /**
+   * Gets available output, outputting to the start of {@code buffer}. The buffer's position will be
+   * advanced by the number of bytes written.
+   *
+   * @param buffer A {@link ShortBuffer} into which output will be written.
+   */
+  public void getOutput(ShortBuffer buffer) {
+    int framesToRead = Math.min(buffer.remaining() / channelCount, outputFrameCount);
+    buffer.put(outputBuffer, 0, framesToRead * channelCount);
+    outputFrameCount -= framesToRead;
+    System.arraycopy(
+        outputBuffer,
+        framesToRead * channelCount,
+        outputBuffer,
+        0,
+        outputFrameCount * channelCount);
+  }
+
+  /**
+   * Forces generating output using whatever data has been queued already. No extra delay will be
+   * added to the output, but flushing in the middle of words could introduce distortion.
+   */
+  public void queueEndOfStream() {
+    int remainingFrameCount = inputFrameCount;
+    float s = speed / pitch;
+    float r = rate * pitch;
+    int expectedOutputFrames =
+        outputFrameCount + (int) ((remainingFrameCount / s + pitchFrameCount) / r + 0.5f);
+
+    // Add enough silence to flush both input and pitch buffers.
+    inputBuffer =
+        ensureSpaceForAdditionalFrames(
+            inputBuffer, inputFrameCount, remainingFrameCount + 2 * maxRequiredFrameCount);
+    for (int xSample = 0; xSample < 2 * maxRequiredFrameCount * channelCount; xSample++) {
+      inputBuffer[remainingFrameCount * channelCount + xSample] = 0;
+    }
+    inputFrameCount += 2 * maxRequiredFrameCount;
+    processStreamInput();
+    // Throw away any extra frames we generated due to the silence we added.
+    if (outputFrameCount > expectedOutputFrames) {
+      outputFrameCount = expectedOutputFrames;
+    }
+    // Empty input and pitch buffers.
+    inputFrameCount = 0;
+    remainingInputToCopyFrameCount = 0;
+    pitchFrameCount = 0;
+  }
+
+  /** Clears state in preparation for receiving a new stream of input buffers. */
+  public void flush() {
+    inputFrameCount = 0;
+    outputFrameCount = 0;
+    pitchFrameCount = 0;
+    oldRatePosition = 0;
+    newRatePosition = 0;
+    remainingInputToCopyFrameCount = 0;
+    prevPeriod = 0;
+    prevMinDiff = 0;
+    minDiff = 0;
+    maxDiff = 0;
+  }
+
+  /** Returns the size of output that can be read with {@link #getOutput(ShortBuffer)}, in bytes. */
+  public int getOutputSize() {
+    return outputFrameCount * channelCount * BYTES_PER_SAMPLE;
+  }
+
+  // Internal methods.
+
+  /**
+   * Returns {@code buffer} or a copy of it, such that there is enough space in the returned buffer
+   * to store {@code newFrameCount} additional frames.
+   *
+   * @param buffer The buffer.
+   * @param frameCount The number of frames already in the buffer.
+   * @param additionalFrameCount The number of additional frames that need to be stored in the
+   *     buffer.
+   * @return A buffer with enough space for the additional frames.
+   */
+  private short[] ensureSpaceForAdditionalFrames(
+      short[] buffer, int frameCount, int additionalFrameCount) {
+    int currentCapacityFrames = buffer.length / channelCount;
+    if (frameCount + additionalFrameCount <= currentCapacityFrames) {
+      return buffer;
+    } else {
+      int newCapacityFrames = 3 * currentCapacityFrames / 2 + additionalFrameCount;
+      return Arrays.copyOf(buffer, newCapacityFrames * channelCount);
+    }
+  }
+
+  private void removeProcessedInputFrames(int positionFrames) {
+    int remainingFrames = inputFrameCount - positionFrames;
+    System.arraycopy(
+        inputBuffer, positionFrames * channelCount, inputBuffer, 0, remainingFrames * channelCount);
+    inputFrameCount = remainingFrames;
+  }
+
+  private void copyToOutput(short[] samples, int positionFrames, int frameCount) {
+    outputBuffer = ensureSpaceForAdditionalFrames(outputBuffer, outputFrameCount, frameCount);
+    System.arraycopy(
+        samples,
+        positionFrames * channelCount,
+        outputBuffer,
+        outputFrameCount * channelCount,
+        frameCount * channelCount);
+    outputFrameCount += frameCount;
+  }
+
+  private int copyInputToOutput(int positionFrames) {
+    int frameCount = Math.min(maxRequiredFrameCount, remainingInputToCopyFrameCount);
+    copyToOutput(inputBuffer, positionFrames, frameCount);
+    remainingInputToCopyFrameCount -= frameCount;
+    return frameCount;
+  }
+
+  private void downSampleInput(short[] samples, int position, int skip) {
+    // If skip is greater than one, average skip samples together and write them to the down-sample
+    // buffer. If channelCount is greater than one, mix the channels together as we down sample.
+    int frameCount = maxRequiredFrameCount / skip;
+    int samplesPerValue = channelCount * skip;
+    position *= channelCount;
+    for (int i = 0; i < frameCount; i++) {
+      int value = 0;
+      for (int j = 0; j < samplesPerValue; j++) {
+        value += samples[position + i * samplesPerValue + j];
+      }
+      value /= samplesPerValue;
+      downSampleBuffer[i] = (short) value;
+    }
+  }
+
+  private int findPitchPeriodInRange(short[] samples, int position, int minPeriod, int maxPeriod) {
+    // Find the best frequency match in the range, and given a sample skip multiple. For now, just
+    // find the pitch of the first channel.
+    int bestPeriod = 0;
+    int worstPeriod = 255;
+    int minDiff = 1;
+    int maxDiff = 0;
+    position *= channelCount;
+    for (int period = minPeriod; period <= maxPeriod; period++) {
+      int diff = 0;
+      for (int i = 0; i < period; i++) {
+        short sVal = samples[position + i];
+        short pVal = samples[position + period + i];
+        diff += Math.abs(sVal - pVal);
+      }
+      // Note that the highest number of samples we add into diff will be less than 256, since we
+      // skip samples. Thus, diff is a 24 bit number, and we can safely multiply by numSamples
+      // without overflow.
+      if (diff * bestPeriod < minDiff * period) {
+        minDiff = diff;
+        bestPeriod = period;
+      }
+      if (diff * worstPeriod > maxDiff * period) {
+        maxDiff = diff;
+        worstPeriod = period;
+      }
+    }
+    this.minDiff = minDiff / bestPeriod;
+    this.maxDiff = maxDiff / worstPeriod;
+    return bestPeriod;
+  }
+
+  /**
+   * Returns whether the previous pitch period estimate is a better approximation, which can occur
+   * at the abrupt end of voiced words.
+   */
+  private boolean previousPeriodBetter(int minDiff, int maxDiff) {
+    if (minDiff == 0 || prevPeriod == 0) {
+      return false;
+    }
+    if (maxDiff > minDiff * 3) {
+      // Got a reasonable match this period.
+      return false;
+    }
+    if (minDiff * 2 <= prevMinDiff * 3) {
+      // Mismatch is not that much greater this period.
+      return false;
+    }
+    return true;
+  }
+
+  private int findPitchPeriod(short[] samples, int position) {
+    // Find the pitch period. This is a critical step, and we may have to try multiple ways to get a
+    // good answer. This version uses AMDF. To improve speed, we down sample by an integer factor
+    // get in the 11 kHz range, and then do it again with a narrower frequency range without down
+    // sampling.
+    int period;
+    int retPeriod;
+    int skip = inputSampleRateHz > AMDF_FREQUENCY ? inputSampleRateHz / AMDF_FREQUENCY : 1;
+    if (channelCount == 1 && skip == 1) {
+      period = findPitchPeriodInRange(samples, position, minPeriod, maxPeriod);
+    } else {
+      downSampleInput(samples, position, skip);
+      period = findPitchPeriodInRange(downSampleBuffer, 0, minPeriod / skip, maxPeriod / skip);
+      if (skip != 1) {
+        period *= skip;
+        int minP = period - (skip * 4);
+        int maxP = period + (skip * 4);
+        if (minP < minPeriod) {
+          minP = minPeriod;
+        }
+        if (maxP > maxPeriod) {
+          maxP = maxPeriod;
+        }
+        if (channelCount == 1) {
+          period = findPitchPeriodInRange(samples, position, minP, maxP);
+        } else {
+          downSampleInput(samples, position, 1);
+          period = findPitchPeriodInRange(downSampleBuffer, 0, minP, maxP);
+        }
+      }
+    }
+    if (previousPeriodBetter(minDiff, maxDiff)) {
+      retPeriod = prevPeriod;
+    } else {
+      retPeriod = period;
+    }
+    prevMinDiff = minDiff;
+    prevPeriod = period;
+    return retPeriod;
+  }
+
+  private void moveNewSamplesToPitchBuffer(int originalOutputFrameCount) {
+    int frameCount = outputFrameCount - originalOutputFrameCount;
+    pitchBuffer = ensureSpaceForAdditionalFrames(pitchBuffer, pitchFrameCount, frameCount);
+    System.arraycopy(
+        outputBuffer,
+        originalOutputFrameCount * channelCount,
+        pitchBuffer,
+        pitchFrameCount * channelCount,
+        frameCount * channelCount);
+    outputFrameCount = originalOutputFrameCount;
+    pitchFrameCount += frameCount;
+  }
+
+  private void removePitchFrames(int frameCount) {
+    if (frameCount == 0) {
+      return;
+    }
+    System.arraycopy(
+        pitchBuffer,
+        frameCount * channelCount,
+        pitchBuffer,
+        0,
+        (pitchFrameCount - frameCount) * channelCount);
+    pitchFrameCount -= frameCount;
+  }
+
+  private short interpolate(short[] in, int inPos, int oldSampleRate, int newSampleRate) {
+    short left = in[inPos];
+    short right = in[inPos + channelCount];
+    int position = newRatePosition * oldSampleRate;
+    int leftPosition = oldRatePosition * newSampleRate;
+    int rightPosition = (oldRatePosition + 1) * newSampleRate;
+    int ratio = rightPosition - position;
+    int width = rightPosition - leftPosition;
+    return (short) ((ratio * left + (width - ratio) * right) / width);
+  }
+
+  private void adjustRate(float rate, int originalOutputFrameCount) {
+    if (outputFrameCount == originalOutputFrameCount) {
+      return;
+    }
+    int newSampleRate = (int) (inputSampleRateHz / rate);
+    int oldSampleRate = inputSampleRateHz;
+    // Set these values to help with the integer math.
+    while (newSampleRate > (1 << 14) || oldSampleRate > (1 << 14)) {
+      newSampleRate /= 2;
+      oldSampleRate /= 2;
+    }
+    moveNewSamplesToPitchBuffer(originalOutputFrameCount);
+    // Leave at least one pitch sample in the buffer.
+    for (int position = 0; position < pitchFrameCount - 1; position++) {
+      while ((oldRatePosition + 1) * newSampleRate > newRatePosition * oldSampleRate) {
+        outputBuffer =
+            ensureSpaceForAdditionalFrames(
+                outputBuffer, outputFrameCount, /* additionalFrameCount= */ 1);
+        for (int i = 0; i < channelCount; i++) {
+          outputBuffer[outputFrameCount * channelCount + i] =
+              interpolate(pitchBuffer, position * channelCount + i, oldSampleRate, newSampleRate);
+        }
+        newRatePosition++;
+        outputFrameCount++;
+      }
+      oldRatePosition++;
+      if (oldRatePosition == oldSampleRate) {
+        oldRatePosition = 0;
+        Assertions.checkState(newRatePosition == newSampleRate);
+        newRatePosition = 0;
+      }
+    }
+    removePitchFrames(pitchFrameCount - 1);
+  }
+
+  private int skipPitchPeriod(short[] samples, int position, float speed, int period) {
+    // Skip over a pitch period, and copy period/speed samples to the output.
+    int newFrameCount;
+    if (speed >= 2.0f) {
+      newFrameCount = (int) (period / (speed - 1.0f));
+    } else {
+      newFrameCount = period;
+      remainingInputToCopyFrameCount = (int) (period * (2.0f - speed) / (speed - 1.0f));
+    }
+    outputBuffer = ensureSpaceForAdditionalFrames(outputBuffer, outputFrameCount, newFrameCount);
+    overlapAdd(
+        newFrameCount,
+        channelCount,
+        outputBuffer,
+        outputFrameCount,
+        samples,
+        position,
+        samples,
+        position + period);
+    outputFrameCount += newFrameCount;
+    return newFrameCount;
+  }
+
+  private int insertPitchPeriod(short[] samples, int position, float speed, int period) {
+    // Insert a pitch period, and determine how much input to copy directly.
+    int newFrameCount;
+    if (speed < 0.5f) {
+      newFrameCount = (int) (period * speed / (1.0f - speed));
+    } else {
+      newFrameCount = period;
+      remainingInputToCopyFrameCount = (int) (period * (2.0f * speed - 1.0f) / (1.0f - speed));
+    }
+    outputBuffer =
+        ensureSpaceForAdditionalFrames(outputBuffer, outputFrameCount, period + newFrameCount);
+    System.arraycopy(
+        samples,
+        position * channelCount,
+        outputBuffer,
+        outputFrameCount * channelCount,
+        period * channelCount);
+    overlapAdd(
+        newFrameCount,
+        channelCount,
+        outputBuffer,
+        outputFrameCount + period,
+        samples,
+        position + period,
+        samples,
+        position);
+    outputFrameCount += period + newFrameCount;
+    return newFrameCount;
+  }
+
+  private void changeSpeed(float speed) {
+    if (inputFrameCount < maxRequiredFrameCount) {
+      return;
+    }
+    int frameCount = inputFrameCount;
+    int positionFrames = 0;
+    do {
+      if (remainingInputToCopyFrameCount > 0) {
+        positionFrames += copyInputToOutput(positionFrames);
+      } else {
+        int period = findPitchPeriod(inputBuffer, positionFrames);
+        if (speed > 1.0) {
+          positionFrames += period + skipPitchPeriod(inputBuffer, positionFrames, speed, period);
+        } else {
+          positionFrames += insertPitchPeriod(inputBuffer, positionFrames, speed, period);
+        }
+      }
+    } while (positionFrames + maxRequiredFrameCount <= frameCount);
+    removeProcessedInputFrames(positionFrames);
+  }
+
+  private void processStreamInput() {
+    // Resample as many pitch periods as we have buffered on the input.
+    int originalOutputFrameCount = outputFrameCount;
+    float s = speed / pitch;
+    float r = rate * pitch;
+    if (s > 1.00001 || s < 0.99999) {
+      changeSpeed(s);
+    } else {
+      copyToOutput(inputBuffer, 0, inputFrameCount);
+      inputFrameCount = 0;
+    }
+    if (r != 1.0f) {
+      adjustRate(r, originalOutputFrameCount);
+    }
+  }
+
+  private static void overlapAdd(
+      int frameCount,
+      int channelCount,
+      short[] out,
+      int outPosition,
+      short[] rampDown,
+      int rampDownPosition,
+      short[] rampUp,
+      int rampUpPosition) {
+    for (int i = 0; i < channelCount; i++) {
+      int o = outPosition * channelCount + i;
+      int u = rampUpPosition * channelCount + i;
+      int d = rampDownPosition * channelCount + i;
+      for (int t = 0; t < frameCount; t++) {
+        out[o] = (short) ((rampDown[d] * (frameCount - t) + rampUp[u] * t) / frameCount);
+        o += channelCount;
+        d += channelCount;
+        u += channelCount;
+      }
+    }
+  }
+
+}